The present invention generally relates to color video signal recording and reproducing apparatuses, and more particularly to a color video signal recording and reproducing apparatus in which a line-sequential color difference signal is obtained by alternately and time-sequentially multiplexing two kinds of color difference signals (including primary color signals) which are obtained from a demodulated signal of a carrier chrominance signal, between a luminance signal and the carrier chrominance signal which make up a color video signal, for every one horizontal scanning period, the line-sequential color difference signal is subjected to a time base compression and is then time-division-multiplexed to the luminance signal so as to obtain a time-division-multiplexed signal, the time-division-multiplexed signal is band-divided into a high-frequency component and a low-frequency component, a frequency modulated signal obtained by frequency-modulating the low-frequency component and a signal obtained by frequency-converting the high-frequency component to a low-frequency band are respectively recorded on a recording medium, and a reproduced color video signal in conformance with a standard system is obtained by subjecting a signal which is reproduced from the recording medium to a signal processing which is in reverse to the signal processing performed at the time of the recording.
Among the existing color video signal recording and reproducing apparatuses such as a video tape recorder (VTR), the popular recording and reproducing apparatus employ the following recording and reproducing method. That is, a luminance signal and a carrier chrominance signal are separated from a composite color video signal of a standard system such as the NTSC, PAL, and SECAM systems. The separated luminance signal is frequency-modulated, and the separated carrier chrominance signal is frequency-converted into a low-frequency band. The frequency converted carrier chrominance signal is frequency-division-multiplexed with the frequency modulated luminance signal, and this frequency-division-multiplexed signal is recorded on a recording medium. At the time of a reproduction, a signal which is reproduced from the recording medium is subjected to a signal processing which is complementary to the signal processing carried out at the time of the recording, so as to obtain a reproduced composite color video signal which is in conformance with the original standard system. In other words, the popular recording and/or reproducing apparatuses employ the so-called low-band conversion recording and reproducing system.
The recording and reproducing apparatus employing the low-band conversion recording and reproducing system, has the following advantages. (I) Because the frequency band of the luminance signal can be selected arbitrarily, the apparatus is especially advantageous when applied to a home use VTR in which the frequency band in which the recording and reproduction can be carried out is relatively narrow. (II) A demodulated chrominance signal is uneasily affected by a time base deviation upon reproduction in the VTR. (III) There is little beat interference because only the luminance signal passes through frequency modulating and frequency demodulating systems, and a pilot signal is not recorded and reproduced. (IV) The frequency modulated luminance signal has a high-frequency biasing effect, and enables recording of the carrier chrominance signal with a satisfactory linearity.
On the other hand, there is a trend to lengthen the recording and reproducing times of the recording and reproducing apparatus, and there is thus a trend to lower the traveling speed of a magnetic tape which is used as the recording medium. Further, there is a demand to enable reproduction of an audio signal with a higher quality. However, since the audio signal is recorded on and reproduced from the magnetic tape by a stationary head, the relative linear velocity between the magnetic tape and the stationary head is small. For this reason, when the traveling speed of the magnetic tape is reduced, the frequency characteristic of the audio signal becomes greatly deteriorated compared to the frequency characteristic of the video signal which is recorded on and reproduced from the magnetic tape by a plurality of rotary video heads. Therefore, it was impossible to record and reproduce the audio signal with a high quality.
Thus, another recording and reproducing system was proposed. According to this proposed recording and reproducing system, the audio signal is converted into a predetermined signal format, and the audio signal having this converted signal format is superimposed on the video signal. The superimposed signal is recorded on and reproduced from the magnetic tape by the rotary video heads. In this proposed recording and reproducing system, the audio signal is recorded on and reproduced from the magnetic tape by the rotary video heads which have a high relative linear velocity with respect to the magnetic tape. For this reason, even in a case where the traveling speed of the magnetic tape is slow, the audio signal can be recorded and reproduced with a quality which is far superior to the quality with which the audio signal can be recorded and reproduced by the stationary head in a state where the traveling speed of the magnetic tape is not reduced.
However, in the recording and reproducing apparatus employing the low-band conversion system described before, two signals, that is, the luminance signal and the carrier chrominance signal must be transmitted in the narrow frequency band. Hence, the frequency band in which the frequency-division-multiplexed signal made up of the frequency modulated luminance signal and the frequency converted carrier chrominance signal is recorded and reproduced, had to be set to a narrow frequency band. Accordingly, the frequency band in which the luminance signal was recorded and reproduced was narrow, and thus, it was impossible to improve the resolution. Moreover, in the proposed recording and reproducing system in which the audio signal is recorded on and reproduced from the same track as the video signal by the rotary video heads with the low-band recording and reproducing system described before, the recording and reproduction were carried out by arranging a frequency modulated audio signal which is obtained by frequency-modulating a carrier by the audio signal into an unoccupied frequency band between the frequency converted carrier chrominance signal and the frequency modulated luminance signal. Therefore, in this proposed recording and reproducing system, the frequency band of the frequency modulated luminance signal became further limited due to the frequency modulated audio signal, and there was a disadvantage in that the resolution became poorer.